A ring-shaped spiral acoustic black hole vibration damping structure

Abstract

The present invention discloses an annular spiral acoustic black hole vibration damping structure, which relates to the technical field of vibration damping and noise reduction. The structure includes a central ring made of a high-temperature resistant material, a plurality of Archimedean spiral acoustic black holes, and an annular belt. The central ring is sleeved on the surface of the tubular structure to be vibration-damped. Each Archimedean spiral acoustic black hole is formed by curling the end of a one-dimensional acoustic black hole in the form of an Archimedean spiral around the tubular structure to be vibration-damped. The first ends of the one-dimensional acoustic black holes are all fixed on the surface of the tubular structure to be vibration-damped through the central ring, and the first ends of the one-dimensional acoustic black holes are evenly arranged in the circumferential direction of the tubular structure to be vibration-damped in the central ring. The thickness of the one-dimensional acoustic black hole decreases exponentially from the first end of the one-dimensional acoustic black hole to the end of the one-dimensional acoustic black hole. The damping annular belt adheres to the outermost contour of the Archimedean spiral acoustic black hole, and each annular belt together constitutes the outermost contour of the vibration damping structure. The present invention is applicable to the vibration damping and noise reduction of tubular structures, and is lightweight and high-temperature resistant.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration and noise reduction, and particularly to an annular spiral acoustic black hole vibration reduction structure. Background Art

[0002] The development of lightweight structures with high vibration reduction performance has always been an important challenge in engineering problems. Since the essence of structural vibration and noise generation is the wave phenomenon generated by multiple reflections of the structure at the boundary, as well as the mutual coupling effect between elastic waves and the surrounding acoustic medium. Therefore, an effective means to achieve structural vibration and noise reduction is to control the elastic waves in the structure. Currently, there are mainly two categories of wave manipulation techniques: active control and passive control. Active control generally requires external energy supply, and the design of the system is also very cumbersome, so at present, its practicality is insufficient and it is difficult to be widely promoted on a large scale. The most common way of passive control is to paste damping materials, but for some large structures, a large amount of damping materials need to be pasted on their surfaces, which not only increases the economic cost, but also introduces too much additional mass, which is not conducive to the lightweight of the structure.

[0003] The Acoustic Black Hole (ABH) effect changes the thickness of the structure, making it change according to a certain power law, thereby changing the structural impedance, resulting in a gradual decrease in the propagation speed of elastic waves in the structure. In an ideal situation, when the thickness decreases to zero, the wave speed also decreases to zero accordingly, resulting in zero reflection and energy concentration of the wave. In actual processing, due to the existence of truncation, the thickness cannot be reduced to zero, but the energy is still concentrated in the area of the minimum thickness of the structure. Therefore, combining a small amount of damping material in the energy concentration area can effectively enhance the structural loss factor, absorb energy, and reduce the vibration of the structure.

[0004] However, existing acoustic black hole structures (traditional acoustic black hole structures) are mostly beam-shaped and disk-shaped structures, mainly designed for flat plate structures, that is, mainly designed for vibrations perpendicular to the plate surface direction. For tubular structures (pipe structures), their vibration directions include not only radial vibrations (bending vibrations) perpendicular to the pipe direction but also circumferential vibrations (torsional vibrations) around the pipe direction. For the multi-directional vibrations generated by such non-planar structures (multi-directional means the bending vibrations along the pipe direction generated when the pipe vibrates, the torsional vibrations generated by pipe torsion, and the bending-torsion vibrations formed by the coupling of bending and torsion), traditional acoustic black holes cannot meet the vibration reduction requirements, that is, traditional acoustic black hole structures are not applicable to the pipe structures widely used in factory construction and production processes.

[0005] Most of the existing vibration reduction methods for pipeline structures are to lay a layer of damping material on the pipeline. This method often adds too much mass to the structure itself, which is not conducive to the requirement of lightweight in production and processing. In addition, since the pipeline structure often faces a high-temperature working environment in actual engineering applications, most damping materials cannot be used under high-temperature conditions.

[0006] In summary, there is an urgent need in the art for a new type of acoustic black hole structure to be applicable to the vibration reduction and noise reduction of tubular structures, while achieving the purposes of lightweight and high temperature resistance. Summary of the Invention

[0007] The object of the present invention is to provide an annular spiral acoustic black hole vibration reduction structure, so as to be applicable to the vibration reduction and noise reduction of tubular structures, while achieving the purposes of lightweight and high temperature resistance.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] An annular spiral acoustic black hole vibration reduction structure, the vibration reduction structure includes a central ring made of a high-temperature resistant material, a plurality of Archimedean spiral acoustic black holes, and a plurality of annular bands;

[0010] The central ring is sleeved on the surface of the tubular structure to be vibration-reduced; each Archimedean spiral acoustic black hole is formed by curling the end of a one-dimensional acoustic black hole in the form of an Archimedean spiral around the tubular structure to be vibration-reduced; each of the one-dimensional acoustic black holes is the same; the first ends of each of the one-dimensional acoustic black holes are fixed on the surface of the tubular structure to be vibration-reduced through the central ring, and the first ends of each of the one-dimensional acoustic black holes are uniformly arranged in the circumferential direction of the tubular structure to be vibration-reduced in the central ring; the first end of the one-dimensional acoustic black hole is the thickest end of the one-dimensional acoustic black hole; the end of the one-dimensional acoustic black hole is the thinnest end of the one-dimensional acoustic black hole; the thickness of the one-dimensional acoustic black hole decreases exponentially from the first end of the one-dimensional acoustic black hole to the end of the one-dimensional acoustic black hole;

[0011] The annular bands are adhered to the outermost contour of the Archimedean spiral acoustic black holes, and each of the annular bands together constitutes the outermost contour of the vibration reduction structure; the Archimedean spiral acoustic black holes are used to absorb and dissipate the bending vibration energy and torsional vibration energy generated at any position on the tubular structure to be vibration-reduced; the annular bands are used to consume the bending vibration energy and the torsional vibration energy.

[0012] Optionally, the number of the Archimedean spiral acoustic black holes is at least 4.

[0013] Optionally, the number of the annular bands is at least 4.

[0014] Optionally, the number of the Archimedean spiral acoustic black holes is equal to the number of the annular bands.

[0015] Optionally, the expression of the exponent is h(x) = εx m + h0; where h(x) represents the thickness of the one-dimensional acoustic black hole; ε represents the coefficient; x represents the length of the one-dimensional acoustic black hole; m is a constant and m ≥ 2; h0 represents the thickness of the thinnest end of the one-dimensional acoustic black hole.

[0016] Optionally, the annular band is a damping material.

[0017] Optionally, the damping material is 3M damping material.

[0018] Optionally, bolt holes are provided on the central ring; the bolt holes are used for fixedly connecting the two tubular structures to be vibration-damped.

[0019] Optionally, the central ring is fixed to the surface of the tubular structure to be vibration-damped by means of bonding or welding.

[0020] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0021] For the annular spiral acoustic black hole vibration damping structure disclosed by the present invention, the first ends of the one-dimensional acoustic black holes are all fixed to the surface of the tubular structure to be vibration-damped through the central ring, and the first ends of the one-dimensional acoustic black holes are evenly arranged in the central ring along the circumferential direction of the tubular structure to be vibration-damped. The second ends of the one-dimensional acoustic black holes are all curled around the tubular structure to be vibration-damped in the form of an Archimedean spiral to form an annular spiral acoustic black hole vibration damping structure. The first ends of the evenly arranged one-dimensional acoustic black holes are fixed to the surface of the tubular structure to be vibration-damped through the central ring, realizing the connection between the annular spiral acoustic black hole vibration damping structure and the tubular structure to be vibration-damped through the ring, and the contact surface covers the entire circumferential surface of the tubular structure to be vibration-damped. Therefore, the annular spiral acoustic black hole vibration damping structure can absorb and dissipate the bending vibration energy and torsional vibration energy generated at any position on the tubular structure to be vibration-damped. By transferring the vibration energy on the tubular structure to be vibration-damped to the variable-thickness region (the Archimedean spiral acoustic black hole is of variable thickness) of the annular spiral acoustic black hole vibration damping structure made of a high-temperature resistant material, combining the characteristics of acoustic black hole vibration damping and noise reduction, and at the same time combining the damping annular band pasted on the variable-thickness region to dissipate the vibration energy, the effects of reducing vibration and then reducing noise and being high-temperature resistant are achieved; in addition, compared with the prior art of laying heavy damping materials on the entire tubular structure to be vibration-damped, only using the annular spiral acoustic black hole vibration damping structure to achieve vibration damping and noise reduction of the tubular structure, the effect of light weight is achieved. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for use in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0023] Figure 1 Structural diagram of an embodiment of the annular spiral acoustic black hole vibration damping structure of the present invention;

[0024] Figure 2 Schematic diagram of a one-dimensional acoustic black hole of the present invention;

[0025] Figure 3 Schematic diagram of an Archimedean spiral acoustic black hole of the present invention;

[0026] Figure 4 Schematic diagram of the formation of CSABH of the present invention;

[0027] Figure 5 Partial three-dimensional view of the annular spiral acoustic black hole vibration damping structure of the present invention;

[0028] Figure 6 Side view of the annular spiral acoustic black hole vibration damping structure of the present invention;

[0029] Figure 7 Front view of the annular spiral acoustic black hole vibration damping structure of the present invention;

[0030] Figure 8 Complete three-dimensional view of the annular spiral acoustic black hole vibration damping structure of the present invention;

[0031] Figure 9 Comparison diagram of the damping characteristics of the uniform pipe and the uniform pipe with an additional annular spiral acoustic black hole vibration damping structure system and an additional control group structure system;

[0032] Figure 10 Comparison diagram of the vibration characteristics of the uniform pipe and the uniform pipe with an additional annular spiral acoustic black hole vibration damping structure system and an additional control group structure system;

[0033] Figure 11 Schematic diagram of punching when CSABH is used as a flange;

[0034] Figure 12 Schematic diagram when CSABH is used as a pipe flange structure to connect two pipes. Detailed implementation manners

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] The object of the present invention is to provide an annular spiral acoustic black hole vibration damping structure, so as to be applicable to the vibration damping and noise reduction of tubular structures, and achieve the purposes of light weight and high temperature resistance at the same time.

[0037] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Figure 1 is a structural diagram of an embodiment of the annular spiral acoustic black hole vibration damping structure of the present invention. Figure 2 is a schematic diagram of a one-dimensional acoustic black hole of the present invention. Figure 3 is a schematic diagram of an Archimedean spiral acoustic black hole of the present invention. Refer to Figure 1 、 Figure 2 and Figure 3 The annular spiral acoustic black hole vibration damping structure includes a central ring 44 made of a high-temperature resistant material, a plurality of Archimedean spiral acoustic black holes 1 and a plurality of annular bands 45. Figure 1 The ellipsis "......" in

[0039] The central ring 44 is sleeved on the surface of the tubular structure A1 to be vibration-damped; each Archimedean spiral acoustic black hole 1 is formed by curling the end of a one-dimensional acoustic black hole 2 in the form of an Archimedean spiral around the tubular structure A1 to be vibration-damped; each one-dimensional acoustic black hole 2 is the same; the head ends a of each one-dimensional acoustic black hole 2 are fixed on the surface of the tubular structure A1 to be vibration-damped through the central ring 44, and the head ends a of each one-dimensional acoustic black hole 2 are evenly distributed in the central ring 44 along the circumferential direction of the tubular structure A1 to be vibration-damped; the head end a of the one-dimensional acoustic black hole 2 is the thickest end of the one-dimensional acoustic black hole 2; the tail end b of the one-dimensional acoustic black hole 2 is the thinnest end of the one-dimensional acoustic black hole 2; the thickness of the one-dimensional acoustic black hole 2 decreases exponentially from the head end a of the one-dimensional acoustic black hole 2 to the tail end b of the one-dimensional acoustic black hole 2. The expression of the exponent is h(x) = εx m + h0; where h(x) represents the thickness of the one-dimensional acoustic black hole 2; ε represents a coefficient; x represents the length of the one-dimensional acoustic black hole 2; m is a constant and m ≥ 2; h0 represents the thickness of the thinnest end of the one-dimensional acoustic black hole 2.

[0040] The annular belt 45 is adhered to the outermost contour of the Archimedean spiral acoustic black hole 1, and the annular belts 45 together constitute the outermost contour of the annular spiral acoustic black hole vibration damping structure; the Archimedean spiral acoustic black hole 1 is used to absorb and dissipate the bending vibration energy and torsional vibration energy generated at any position on the tubular structure A1 to be vibration-damped; the annular belt 45 is used to consume the bending vibration energy and torsional vibration energy.

[0041] Among them, the number of Archimedean spiral acoustic black holes 1 is at least 4. The number of annular belts 45 is at least 4. The number of Archimedean spiral acoustic black holes 1 is equal to the number of annular belts 45.

[0042] Specifically, the annular belt 45 is a damping material. The damping material is 3M damping material.

[0043] The central ring 44 is fixed to the surface of the tubular structure A1 to be vibration-damped by bonding or welding. The first ends a of the one-dimensional acoustic black holes 2 are all fixed to the surface of the tubular structure A1 to be vibration-damped and connected into a whole through the central ring 44. The one-dimensional acoustic black holes 2 are connected together through the central ring 44.

[0044] As an alternative embodiment, bolt holes are provided on the central ring 44; the bolt holes are used for fixedly connecting two tubular structures A1 to be vibration-damped.

[0045] The following takes a specific embodiment to illustrate in detail the technical solution of the annular spiral acoustic black hole vibration damping structure of the present invention:

[0046] The annular spiral acoustic black hole vibration damping structure proposed by the present invention is based on the fact that the circular spiral acoustic black hole (CSABH) has a low fundamental frequency, a high modal density, and a high matching degree with the natural frequency of the main structure, and can generate a dynamic vibration absorption effect in a wider frequency domain, improve the coupling effect between the acoustic black hole and the main structure, increase the loss factor of the structure, and then suppress the vibration energy of the structure to achieve the effect of broadband vibration damping. Since the CSABH is connected to the pipeline through a ring (central ring 44), the contact surface covers the circumferential surface of the entire pipeline structure, and can absorb and dissipate the bending vibration and torsional vibration energy generated at any position on the pipeline, so as to achieve the purpose of vibration damping in multiple directions.

[0047] 1. The surface formula of CSABH

[0048] CSABH is obtained by arranging k Archimedean spiral ABH1 around the center O. Taking a single branch of CSABH as the research object, with O as the origin, a polar coordinate system (r,θ) is established, as Figure 3 shown. Where R is the outer radius of the spiral; r is the inner radius of the spiral; n is the number of turns of the spiral; θ is the rotation angle. Its curve equation is as follows:

[0049] r(s) = R - (R - r)s

[0050] q(s) = 2πns

[0051] s ∈ [0, 1]

[0052] In the formula, q represents how many degrees the spiral rotates from the starting point to the ending point, and s represents a variable used to define the radius of each point on the spiral line.

[0053] The function of the curve equation is to describe the curve of the spiral ABH region on the CSABH, which is convenient for adjusting and designing the CSABH structure by changing the parameters in the equation. Among them, the contour of the Archimedean spiral ABH1, as Figure 3 shown, is formed by curling the one-dimensional ABH2 contour of Figure 2 in the form of an Archimedean spiral. The parameters of its variable-thickness region are the same as those of the variable-thickness region of the one-dimensional ABH2. The variable-thickness region of the one-dimensional ABH2 satisfies h(x) = εx m + h0. Figure 3 and Figure 2 The solid line parts in are all variable-thickness regions, that is, the ABH regions are all of variable thickness. Figure 3 and Figure 2 show the CSABH surface.

[0054] 2. Formation of CSABH

[0055] The CSABH studied as an example in the present invention is obtained by arraying 4 Archimedean spirals ABH1 around the center O. That is, taking the ring-shaped spiral acoustic black hole damping structure including 4 Archimedean spiral acoustic black holes as an example, the ring-shaped spiral acoustic black hole damping structure of the present invention will be described in detail. The formation process of the ring-shaped spiral acoustic black hole damping structure of the present invention is as Figure 4 shown, Figure 4 is the schematic diagram of the CSABH structure of the present invention, that is, the schematic diagram of the formation of CSABH. Figure 4 Part (a) in represents the schematic diagram of an Archimedean spiral ABH. Figure 4 Part (b) in represents the schematic diagram of four Archimedean spirals ABH. Figure 4 Part (c) in represents the schematic diagram of the formed CSABH. The CSABH formation process is that an Archimedean spiral ABH, as Figure 4 shown by the solid line part in part (a), arrays the other three around the dotted-line ring (central ring 44). It can also be understood that an Archimedean spiral ABH rotates and duplicates the other three around the dotted-line ring, and jointly forms 4 Archimedean spirals ABH with the other three, as Figure 4 shown by the solid line part in part (b). Figure 4The formation (modeling) process of CSABH is represented by parts (a), (b), and (c). Figure 4 In it, part (b) is a perspective view of part (c) and also the array process of part (a). When CSABH is fully formed, that is Figure 4 the form of part (c). The a-end part (thick part) of the Archimedean spiral ABH and Figure 4 the dotted-line ring in the middle of parts (a) and (b) merge into one when finally formed. Therefore Figure 4 it is not necessary to display it again in the representation of part (c). The dotted-line ring actually exists. The significance of the ring's existence is to connect the four Archimedean spirals ABH to form a whole and install it on the tubular structure A1 to be vibration-damped. Merging into one means that the front view of the final CSABH (without damping) is Figure 4 the form shown in part (c). The existence of the dotted-line ring cannot be directly seen with the naked eye. The four Archimedean spirals ABH are connected into a whole through the central ring 44 to form a structure, that is, the CSABH structure. The front view of CSABH without damping is Figure 4 the form shown in part (c). In addition, the a-end parts of each Archimedean spiral ABH do not have to be spaced at a quarter of a circular arc. In this invention, the discussion is carried out taking the spacing at a quarter of a circular arc as an example, and the specific spacing can be determined according to the research object required.

[0056] 3. Vibration Damping of CSABH

[0057] Figure 5 This is a partial perspective view of the annular spiral acoustic black hole vibration damping structure of the present invention. Figure 6 This is a side view of the annular spiral acoustic black hole vibration damping structure of the present invention. Figure 7 This is the front view of the annular spiral acoustic black hole vibration damping structure of the present invention. As shown in Figure 5 , Figure 6 and Figure 7 shown, the annular spiral acoustic black hole vibration damping structure A2 of the present invention includes: a central ring 44 and an Archimedean spiral ABH around the central ring 44. The annular spiral acoustic black hole vibration damping structure A2 is arranged on the controlled structure (tubular structure to be vibration-damped) A1.

[0058] The central ring 44 is composed of a second circle 42 (i.e., the pipe outer wall 42) and a third circle 43. The inner diameter of the pipe of the controlled structure A1 is the first circle 41, the outer diameter of the pipe is the second circle 42. The centers of the first circle 41, the second circle 42, and the third circle 43 are the same, and the second circle 42 and the third circle 43 are in the same plane.

[0059] The annular spiral acoustic black hole vibration damping structure A2 is connected to the controlled structure A1 through the second circle 42. The second circle 42 is the outer wall of the pipe. There is no need to drill holes in the outer wall of the pipe. The second circle 42 is shared by the pipe and the CSABH. It is both the outer wall of the pipe and the inner wall of the CSABH. When the vibration damping structure A2 is connected to the controlled structure A1, the CSABH can be sleeved on the pipe, and they can be connected by gluing or welding at the contact surface between the two.

[0060] The thickness of the acoustic black hole part (Archimedean spiral ABH) decreases exponentially with the thickness of the one-dimensional ABH, and the one-dimensional ABH is bent into the form of an Archimedean spiral around the central ring 44. Among them, the thickness of the acoustic black hole part is the thickness of the one-dimensional ABH. The exponential expression is h(x) = εx m + h0, where h(x) represents the thickness of the acoustic black hole part (the thickness of the variable thickness region), ε represents the coefficient, x represents the length of the one-dimensional ABH, m ≥ 2, and h0 represents the minimum thickness of the acoustic black hole part. The determination method of ε is: first determine Figure 2 the values of the minimum thickness h0 and the maximum thickness h1 of the acoustic black hole part in Figure 2 the xy coordinate system in m and substitute the points into the expression h(x) = εx

[0061] The annular spiral acoustic black hole vibration damping structure of the present invention further includes an annular belt 45. The function of the annular belt 45 is to consume most of the elastic wave energy (vibration energy). The annular belt 45 is a damping material. The annular belt 45 adheres above the contour of the Archimedean spiral ABH and is pasted with an appropriate length from the minimum thickness of the Archimedean spiral ABH to the maximum thickness. Among them, the damping does not need to be pasted above the entire contour of the Archimedean spiral ABH. It can be pasted from the minimum thickness of the ABH to the maximum thickness. The specific length of the pasted damping annular belt can be determined by oneself. In theory, the more damping is pasted, the better, but in order to reduce the mass, often only pasting a small part can also achieve an ideal vibration damping effect.

[0062] Specifically, the damping material of the annular belt 45 is 3M damping material.

[0063] The annular spiral acoustic black hole vibration damping structure of the present invention is based on the fact that the elastic wave in the solid medium decreases according to a certain power-law function with the structure thickness, and its corresponding phase velocity and group velocity also decrease, so that within a certain spatial scale, the broadband elastic wave is concentrated in the region with a thinner thickness, such as Figure 5As shown, the vibration energy on the controlled structure A1 can be transferred to the annular spiral acoustic black hole vibration damping structure A2 through the central ring 44. In the acoustic black hole region (Archimedean spiral ABH) of the annular spiral acoustic black hole vibration damping structure A2, the wave propagation speed decreases with the decrease of thickness, the wavelength decreases, the vibration amplitude of the wave increases, and it gathers towards the region with smaller thickness. By combining with the damping material 45, most of the elastic wave energy is consumed, so as to achieve the purpose of high-efficiency energy absorption or vibration damping and noise reduction.

[0064] In addition, when using the annular spiral acoustic black hole vibration damping structure of the present invention to achieve vibration damping and noise reduction of a tubular structure, the number of the annular spiral acoustic black hole vibration damping structures of the present invention can be selected according to the actual situation. Using only one annular spiral acoustic black hole vibration damping structure of the present invention can also achieve vibration damping and noise reduction of the tubular structure. However, considering the symmetry of the vibration mode of the controlled pipeline in this embodiment, if the annular spiral acoustic black hole vibration damping structure of the present invention is installed in the region at the left end, the vibration suppression effect on the left end of the pipeline is the best. Similarly, installing the annular spiral acoustic black hole vibration damping structure of the present invention at the right end has the best vibration suppression effect on the right end region of the pipeline. Therefore, in order to control the vibration of the whole pipeline and achieve the best vibration control effect, it is best to install an annular spiral acoustic black hole vibration damping structure of the present invention at each position with the largest vibration displacement at both ends of the pipeline. In principle, the annular spiral acoustic black hole vibration damping structure of the present invention should be installed at the position with the largest displacement when the pipeline vibrates.

[0065] Figure 8 is a perspective view of the annular spiral acoustic black hole vibration damping structure of the present invention, that is, a complete perspective view of the annular spiral acoustic black hole vibration damping structure. As Figure 8As shown in the figure, a hollow uniform pipe structure with a length of 1700 mm, an outer diameter of 66 mm, and an inner diameter of 60 mm is taken as the controlled object (controlled structure) A1. Two ring-shaped spiral acoustic black holes (CSABHs) are attached to both ends of the hollow pipe. The ring-shaped spiral acoustic black hole vibration damping structure includes a second circular diameter of 66 mm and a third circular diameter of 75 mm for the central ring. The outer radius R of the spiral is 63.5 mm, the inner radius r of the spiral is 37.5 mm, the number of turns n of the spiral is 1, and the rotation angle θ is 0°. The minimum thickness h0 of the acoustic black hole region (Archimedean spiral ABH) is 0.5 mm, and the maximum thickness h1 is 4.5 mm. The material of the hollow circular pipe is selected as aluminum, and the material of the ring-shaped spiral acoustic black hole is selected as photosensitive resin. The ring-shaped spiral acoustic black hole vibration damping structure also includes a ring belt 45, and the ring belt 45 is a damping material with a length of 83.56 mm, a width of 20 mm, and a thickness of 1 mm. The 3M damping material is selected for arrangement, and the material loss factor (loss factor) is set to 0.2. At the same time, for comparative research, a ring-shaped spiral structure with the same mass and uniform thickness is also designed as a control group. Among them, the ring-shaped spiral structure with the same mass and uniform thickness is the circular spiral equal mass structure (CSEM).

[0066] The width of the ring belt damping material is the same as that of the CSABH, and the thickness is 1 mm determined according to the thickness of common damping materials in practice. The pasting thickness does not exceed the black hole region, and more damping materials are selected to be pasted without adding too much extra mass.

[0067] The ring-shaped spiral acoustic black hole vibration damping structure is modeled in ABAQUS by the finite element method, and the damping level and vibration velocity response of the ring-shaped spiral acoustic black hole vibration damping structure are calculated through steady-state dynamic analysis and the mode superposition method.

[0068] Analysis of calculation results:

[0069] (1) Damping characteristic analysis

[0070] As Figure 9As shown in the figure, the ring-shaped spiral acoustic black hole vibration damping structure of the present invention can greatly improve the inherent damping level of the structure, and the system damping ratio is increased by 5-80 times in the full frequency band. While the ring-shaped spiral structure with equal mass (ring-shaped spiral equal mass structure) has only a 1-20 times increase due to the properties of the resin material. Compared with it, the inherent damping level of CSABH increases significantly. In the entire frequency band range of 100Hz-5000Hz, the system damping ratio of CSABH is increased several times compared with the control group. All in all, the CSABH structure can greatly improve the damping characteristics of the uniform pipe structure, and is more superior than the ring-shaped spiral structure with equal mass (ring-shaped spiral equal mass structure), which has potential benefits for the vibration suppression of elastic structures. At the same time, because of the lighter mass, it will not cause damage to the controlled object.

[0071] (2) Vibration control characteristic analysis

[0072] As Figure 10 shown, in order to evaluate the vibration level of the system, the origin response of the system is selected as an index for evaluation. It can be found from Figure 10 that after adding the ring-shaped spiral acoustic black hole vibration damping structure of the present invention, compared with the structure before being controlled, the resonance peaks at all frequencies in the entire frequency band are reduced by 8-35dB. This is because the ring-shaped spiral acoustic black hole vibration damping structure of the present invention has a very high modal damping ratio due to the acoustic black hole effect, dynamic vibration absorption effect and the good directivity and robustness brought by the torsional mode generated by the spiral design, and can adapt to the vibration energy coming from multiple directions in a relatively wide frequency band range, exert its vibration damping characteristics, absorb the vibration energy on the controlled structure, and reduce the vibration level of the system. In addition, compared with the system with the ring-shaped spiral structure with equal mass (ring-shaped spiral equal mass structure) added, the system with the ring-shaped spiral acoustic black hole structure of the present invention added has a vibration attenuation of 0-26dB at the resonance peaks in the full frequency band. The reason is that the design of the variable thickness at the edge of the ring-shaped spiral acoustic black hole structure changes the impedance of the structure, resulting in a gradual decrease in the propagation speed of elastic waves in the structure, and making the vibration energy concentrated in the area with the minimum thickness of the structure. By combining a small amount of damping material in the energy concentration area, the structural loss factor can be effectively enhanced, the energy can be absorbed, and the vibration of the structure can be reduced.

[0073] The annular spiral acoustic black hole vibration damping structure of the present invention ingeniously combines the characteristics of the acoustic black hole structure, the dynamic vibration absorber structure, and the Archimedean spiral structure, avoiding the limitations of traditional acoustic black holes in vibration control, which can only control plate-like structures and have limited directivity in controlling elastic waves. Moreover, the spiral design improves the modal density of the structure while saving space, enabling a single device to control multiple modes of the controlled object and achieving an efficient vibration damping effect. The present invention can be parameter-designed according to the frequency characteristics of the controlled object, further improving the broadband characteristics.

[0074] The annular spiral acoustic black hole vibration damping structure of the present invention has a small additional mass, is easy to meet engineering applications, and has the characteristics of high efficiency.

[0075] The annular spiral acoustic black hole (CSABH) structure proposed by the present invention, that is, the annular spiral acoustic black hole vibration damping structure, can broaden the frequency band range of the ABH and increase the directivity of the ABH for vibration control by designing the ABH into a spiral. At the same time, the connection design between the central ring 44 and the pipe wall (outer wall of the tubular structure) also increases the contact surface between the ABH and the pipe (tubular structure), ensuring that the vibration on the pipe is fully transmitted to the acoustic black hole area above the ring, achieving the purpose of broadband and multi-directional vibration damping. Its vibration control is effective not only for the radial vibration perpendicular to the pipe direction but also solves the circumferential vibration around the pipe direction that cannot be controlled by ordinary acoustic black holes. And bolt holes are drilled at the central ring 44, that is, holes are drilled on the CSABH as a new flange structure to replace the commonly used flange structure, such as Figure 11 shown, so that the annular spiral acoustic black hole structure (annular spiral acoustic black hole vibration damping structure) can replace the traditional flange structure for connecting pipes, making it a flange structure that can damp vibration. Drilling holes at the central ring 44 is to replace the flange structure to connect two pipes. If only the vibration damping function of the CSABH is used, it can be sleeved on the pipe by bonding, welding, etc. without drilling holes. If it is used as a flange for drilling, reference can be made to Figure 11 . The schematic diagram when the CSABH is used as a pipe flange structure to connect two pipes is as shown in Figure 12 .

[0076] The proposed ring-shaped spiral acoustic black hole (CSABH) structure of the present invention can be made of high-temperature resistant materials. Combining the vibration reduction and noise reduction characteristics of the acoustic black hole, it achieves the goals of light weight, high temperature resistance, and broadband vibration reduction. Among them, the vibration reduction and noise reduction of the acoustic black hole are realized by transferring the vibration energy on the pipeline to the variable thickness area of the CSABH structure, and combining the damping material pasted on it to dissipate the vibration energy, so as to achieve the effect of reducing vibration and then reducing noise, thus solving the problem of vibration reduction and noise reduction of the tubular structure. The structure of the present invention is lighter in mass than the controlled main structure (the pipeline structure to be vibration-reduced). Taking the example in the present invention, installing two CSABHs to achieve a good vibration reduction effect only increases the mass of the main structure by 5.6%. However, the traditional vibration reduction of pipelines often uses heavy damping materials laid on the entire pipeline, and its additional mass often exceeds 10% or even more. Therefore, the structure of the present invention can achieve a light weight effect.

[0077] Compared with the prior art, the advantages of the present invention are as follows:

[0078] 1. Design the traditional acoustic black hole structure into a spiral form and enable it to be applied to the pipeline system by combining a ring structure.

[0079] 2. Design the outer acoustic black hole part of the ring-shaped spiral acoustic black hole into a spiral form, which can increase the directivity of the vibration control of the pipeline structure.

[0080] 3. Design the acoustic black hole part into a spiral form, which can improve the modal density on the premise of saving installation space, enhance the coupling effect between the ABH and the main structure, and greatly increase the loss factor of the structure in the broadband range, thus broadening the frequency band range of vibration control.

[0081] 4. The ring-shaped spiral acoustic black hole is mainly designed by combining three main structures: the acoustic black hole, the dynamic vibration absorber, and the Archimedes spiral structure.

[0082] 5. Design the acoustic black hole into a ring form that can be applied to the pipeline structure.

[0083] 6. The ring-shaped spiral acoustic black hole can be used as a new type of flange structure with vibration reduction function to establish the connection between pipelines.

[0084] 7. CSABH is obtained by arranging k single spiral ABHs (Archimedes spiral ABHs) around the center of the circle. Usually, k≥4 is sufficient. The structures formed by arranging other numbers in the array have the same essential principle and vibration reduction mechanism as those mentioned in the present invention.

[0085] 8. The annular spiral acoustic black hole (CSABH) structure can be made of various materials with high temperature resistance, etc., and can adapt to various complex working conditions during pipeline operation, avoiding the damage of the vibration damping structure under harsh working conditions. And due to the characteristics of its acoustic black hole structure, it can achieve the purposes of light weight, high temperature resistance, and broadband vibration damping.

[0086] 9. The annular spiral acoustic black hole (CSABH) structure can be installed on the pipeline as a flange structure of the pipeline, which can replace the traditional flange structure and avoid adding other unnecessary vibration damping structures to the pipeline for vibration damping.

[0087] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0088] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A ring-shaped spiral acoustic black hole vibration damping structure, characterized in that, The damping structure includes a central ring made of a high-temperature resistant material, a plurality of Archimedean spiral acoustic black holes, and a plurality of annular bands; The central ring is sleeved on the surface of the tubular structure to be damped; each of the Archimedean spiral acoustic black holes is formed by curling the end of a one-dimensional acoustic black hole in the form of an Archimedean spiral around the tubular structure to be damped; each of the one-dimensional acoustic black holes is the same; the first ends of each of the one-dimensional acoustic black holes are fixed to the surface of the tubular structure to be damped through the central ring, and the first ends of each of the one-dimensional acoustic black holes are evenly distributed in the circumferential direction of the tubular structure to be damped in the central ring; The first end of the one-dimensional acoustic black hole is the thickest end of the one-dimensional acoustic black hole; the end of the one-dimensional acoustic black hole is the thinnest end of the one-dimensional acoustic black hole; the thickness of the one-dimensional acoustic black hole decreases exponentially from the first end of the one-dimensional acoustic black hole to the end of the one-dimensional acoustic black hole; The annular bands are adhered to the outermost contour of the Archimedean spiral acoustic black holes, and each of the annular bands together constitutes the outermost contour of the damping structure; the Archimedean spiral acoustic black holes are used to absorb and dissipate the bending vibration energy and torsional vibration energy generated at any position on the tubular structure to be damped; the annular bands are used to consume the bending vibration energy and the torsional vibration energy.

2. The annular spiral acoustic black hole vibration damping structure according to claim 1, wherein The number of the Archimedean spiral acoustic black holes is at least 4.

3. The annular spiral acoustic black hole vibration damping structure according to claim 1, characterized in that The number of the annular bands is at least 4.

4. The annular spiral acoustic black hole vibration damping structure according to claim 1, characterized in that, The number of the Archimedean spiral acoustic black holes is equal to the number of the annular bands.

5. The annular spiral acoustic black hole vibration damping structure according to claim 1, characterized in that The expression of the exponent is h(x) = εx m + h0; where h(x) represents the thickness of the one-dimensional acoustic black hole; ε represents the coefficient; x represents the length of the one-dimensional acoustic black hole; m is a constant and m ≥ 2; h0 represents the thickness of the thinnest end of the one-dimensional acoustic black hole.

6. The annular spiral acoustic black hole vibration damping structure according to claim 1, wherein The annular bands are damping materials.

7. The annular spiral acoustic black hole vibration damping structure according to claim 6, wherein The damping material is 3M damping material.

8. The annular spiral acoustic black hole vibration damping structure according to claim 1, characterized in that, Bolt holes are provided on the central ring; the bolt holes are used for fixedly connecting two of the tubular structures to be damped.

9. The annular spiral acoustic black hole vibration damping structure according to claim 1, wherein The central ring is fixed to the surface of the tubular structure to be damped by means of bonding or welding.

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